Process for removing asphaltenes from crude oil



p 1, 1953 E. N. CASE 2,650,898

PROCESS FOR REMOVING ASPHALTENES FROM CRUDE OIL Filed Oct. 27, 1951TOPPING STILL o O Ill -S .J 5 Q; m (23 cu 58 w n-m f g m U n INVENTOR.ii a Everet'? N. Case i' BY dafm mmmzzzw IQTTORNEYS Patented Sept. 1,1953 ,7 2,650,898 UNITED STATES PATENT OFFICE PROCESS FOR REMOVING.ASPHALTENES- FROM" CRUDE. OIL

corporationof Maine Application October 27, 1951;. SerlalNb. 253,509 2Claims.. (01. 1963-39) My invention relates to improvements intherefining of crude oil. More particularly, it relates to a-method for:treating the crude oil. prior to conventional refining practices with.a. precipitating' agent whichselectively precipitates certain asphalticrconstituents such asasphaltenes; metal. contaminants, salt and like:deleterious substances; invention provides a simpleandinexpensivermethod' for improving?- the efiiciency of conventionalrefining processes such as distillation and solvent extraction, ffllfimproving the-effectiveness of catalytic cracking processes or:conversely for making available increased. supplies of suitablecatalytic cracking. charge stock, and for increasing the not availablerecovery of marketable oil per barrel of crude processed.

, I have discovered that: certain asphaltic con stituents suchasasphaltenes can be: selectively precipitated from crudeoil by contactingthe crude with gaseous hydrogen chloride. The asphal'tenes' precipitateusually immediately on contact with the precipitating agent an'd may beseparated from the crude by gravity settling, filitration orcentrituging.

Hydrogen chloride is soluble in crude oil. to the; extent: of about .2weight percent. The per cent of asphaltenesprecipitated appearstoincrease up. to'the pointof saturation of the oil with the gas. I havefound, however; that it is particularly advantageousto employsuperatmospheric: pressure, e'. g. from about to ab0ut I50--20'0-p. s.i. g'.. The per cent of asphaltenes precipitated then is great:- lyincreased. The concentration of the-precipitating agent thus may beregulated by pressure for particular crude oils which vary in asphaltic:content or in content of metals and saltand which vary somewhat insolubility for hydrogen chloride. Ordinary temperatures should beemployed.

For example, I have found that operations at ele-- vated temperature, e.g. 300 F.,' even with pres sures of 50 to. 150p. s. i'. g. resultinreduced pre-- cipitation of asphaltenes'. The effectiveness otthetreatment is increased by mild agitation which as sists in: saturatingthe crude oil with the precipitating agent.

I have: found; that; invention is particularly applicable to crude: oilswhich. have. not. been subjected to desaltingoperation: or which havenot. beentopped by removal-(of light. boiling distillate fractions. Thedesaltingprocess seems. to reducethe. efiectiveness oi the: agent in.precipitating. asphaltenes. Although treatment ofi'topped. crudes istechnically feasible, the higher viscosity of the topped crudeinterferes with intimacy of contacting and eifective saturation of thecrude oil with the. precipitating agent. Also, application of. thetreatment to topped crudes is disadvantageous in the sense that the heatput into the crude in the topping operation should be removed by coolingfor effective asphaltenes: precipitation, where?- as. thermal. economicswithin. the: usual: refinery require conservation of heat by running thehot topped crude directly to succeeding distillation or is introduced atthe bottom of tank. H through line I 2. Tank l l is equipped withhydrogen chloride ventline l3 which runs into hydrogen chloriderecycleline l4 and associated compressor l5 for. recycling to tank H. Aft'ersaturation of the crude in tank I l with hydrogen chloride gas underappropriate conditions of temperature and pressure, the treated crude ispermitted to settle for a period of about 3v to 10 or 12v hours.Thetreated crude then is withdrawn from tank II. bymeans. of swing lineI6 and connection H and. charged to topping still l8.

Heat for thedistillation process is provided. by circulating oil fromthe bottom of still I8 through line l9 and heater 20 with return to thestill i8 by'means of connection 21-; Hydrogen chloride'is removedoverheadi from still- I 8 through line 22 and knockout drum 22a forreturn to the treating system by means of line M. A- slipstream of gasmay be purged from the system through connection 23* if build up offixed hydrocarbon gases tends to occur. Distillate fractions are removedas side streams atvarious levels of" still is in the usual manner asindicated by connections 2-4, 25 and Z6. Treated residual. oil may beremoved as: bottoms through line 2?.

Although I have shown only-a single tank treating and separating uni-tthe drawing, obviously the operations of my invention are facilitated byproviding aplurality of tanks connected preferably to a common hydrogenchloride circulating system, in order to maintain continuous supply ortreated cru'deto crude oildistillation units. Asnoted above, thetreatingvessel advantageously is operated under superatmosphericpressure. I have found that pressures of about 15 to p; s; i. g;hydrogen chloride are very effective. Higher pressures do not appear toincrease materially the amount of asphaltenes precipitated. The amountof precipitating agent required is subject to variation with the natureof the crude oil to be treated and the temperature and pressure of thetreatment, but I have found that about 0.1 to 0.9 pound of hydrogenchloride per barrel of. crude oil is usually sufficient. In. any event,it..is.advisable toprovid'eat least enough ofQt-hev precipitating. agenttov saturate the crude with the agent.v

The principles of my invention will be, further,

3 illustrated in the following examples of treatments under variousconditions:

Examples The crude oil was charged to a vessel equipped with amechanical agitator or to a vessel which could be shaken by hand. To thecrude was added the specified amount of gaseous hydrogen sive means forpretreating crude oil prior to conchloride followed by agitation. Theasphaltenes precipitated immediately and either collected on the wallsof the vessel or were present. as solid particles in the crude oil. Thecharge was removed from the vessel and centrifuged to remove theprecipitate. The same end was attainable by about 12 hours gravitysettling. The clean crude layer was decanted and the precipitate waswashed with straight run gasoline to remove the trapped crude. The washliquid may be centrifuged or settled if necessary. The asphaltenesprecipitate was weighed to determine yield. 4

Where the precipitate adhered to the container walls, it was recoveredby solution in benzene and the benzene was removed by distillation togive a residue of asphaltenes.

Using the above procedure the following tests were run on Mid-Continentcrude which had been topped to 400 F. by removal of 31.5% overhead,increasing the density to 0.87:

Wt. Percent Asphaltenes Yield Charge Vol. 1101 Gas C1 50 p. s. i. g. H01at 300 F. 150 p. s. i. g. 1101 at 300 F p. s. i. g. HCl

In a similar test, the crude was first desalted. A charge of 700 ml. ofdensity 0.808 was saturated with hydrogen chloride gas at 50 p. s. i. g.The weight per cent yield of asphaltenes amounted only to 2.1% or 2.78%when corrected to the 68.5% bottoms basis of the foregoing runs.

In a similar example, 700 ml. of untreated Poza Rica (Venezuela) crudeoil of density 0.878 was saturated with hydrogen chloride gas at 50 p.s. i. g. The weight per cent yield of asphaltenes amounted to 6.92% or9.10% corrected to a 68.5% bottoms basis.

As Re- Precipi- Crude ceived tate Residue p. p. m. NiO 9. 5 300 3. 6 p.p. m. V205 18.8 l, 060 8 Hence the metals content of crude oil can besubstantially reduced by application of my invention.

In another example, a topped Mid-Continent crude (69% bottoms) having acarbon residue of 3.0 weight per cent was treated by saturationventional refinery processing. Removal of a substantial proportion ofthe asphaltic constituents of the crude before the oil is subjected tothermal processing such as cracking, vis-breaking or vacuum distillationincreases significantly the yield of the more valuable oil fractions perbarrel of crude processed. The net production of coke or asphalt isreduced and thereby reduces significantly the amount of low valueresiduum which must be disposed of in the form of heavy fuel oils orasphalt. About 40 to of the content of solid asphalt represents valuableheavy oil constituents which are normally lost. My invention thusincreases potential oil recovery in proportion to the reduction inasphalt residuum. Also disposal of the heavy residuum as fuel oilrequires expenditure of considerable amounts of distillate oil as cutterstock. Any decrease in the amount of residuum therefore conserves oil byreducing the requirements for cutter stock.

One of the limiting factors on utilization of heavy gas oil stocks ascharge to catalytic cracking units is the carbon residue of the chargestock which deleteriously affects product distribution in the crackingreaction and reduces capacity of the unit by increasing the burden onthe coke-burning capacity of the catalyst regeneration equipment.Application of my invention permits utilization of heavier gas oilstocks without deleteriously affecting product distribution and withoutoverburdening the coke-burning capacity of the catalytic cracking unit.Application of my invention is of further value in promoting theeconomics of catalytic cracking by reducing substantially the metalscontent of the cracking charge stocks. The result is improved catalystlife and a substantial reduction in the rate at which catalyst must bediscarded from the unit to maintain a desired equilibrium activitylevel.

In lubricating oil refining and production, application of my inventionfacilitates deasphalting and solvent extraction operations and resultsin improved raffinate yields.

I claim:

1. A method for removal of asphaltenes and metal contaminants from crudeoil prior to desalting and conventional refining procedures whichcomprises saturating the crude at a pressure from 15 to 200 pounds persquare inch gauge with a precipitating agent consisting of gaseoushydrogen chloride and separating the agent and precipitated matter fromthe treated crude.

2. A method of removal of asphaltenes and metal contaminants from crudeoil prior to desalting and conventional refining procedures whichcomprises saturating the crude at a pressure from 15 to 200 pounds persquare inch gauge with gaseous hydrogen chloride, separatingprecipitated matter from the treated crude and recovering hydrogenchloride from the treated crude by distillation.

EVERETT N. CASE.

References Cited in the file of this patent UNITED STATES PATENTS

1. A METHOD FOR REMOVAL OF ASPHALTENES AND METAL CONTAMINANTS FROM CRUDEOIL PRIOR TO DESALTING AND CONVENTIONAL REFINING PROCEDURES WHICHCOMPRISES SATURATING THE CRUDE AT A PRESSURE FROM 15 TO 200 POUNDS PERSQUARE INCH GAUGE WITH A PRECIPITATING AGENT CONSISTING OF GASEOUSHYDROGEN CHLORIDE AND SEPARATING THE AGENT AND PRECIPITATED MATTER FROMTHE TREATED CRUDE.